Ultra-high precision comb-locked terahertz frequency-domain spectroscopy of whispering-gallery modes

What is it about?

Frequency comb technology has revolutionized high-precision frequency synthesis and measurements in the optical domain. The optical-frequency synthesizer (OFS) based on a cw-laser locked to an externally shifted frequency comb, allows for wide tuning at unprecedented precision and reproducibility. The OFS extends comb technology to the terahertz (THz) domain (0.1 – 10 THz) by providing a tunable difference frequency to drive a photonic frequency domain THz-Spectrometer. We demonstrate the capabilities of the novel setup by performing ultra-high-precision measurements of high-quality THz whispering-gallery-mode resonances. The unprecedented stability and resolution of the system allows, for the first time, to observe tiny red and blue shifts of the modes due to the presence of a coupling waveguide.

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Photo by FlyD on Unsplash

Photo by FlyD on Unsplash

Why is it important?

The results are of significant interest to an audience specializing in photonics and THz technologies. The findings are a critical advancement in frequency comb-based technology and high-precision THz spectroscopy. The presented system is an ideal platform for developing highly sensitive and selective THz sensors. We, therefore, expect our results to have a far-reaching impact across fundamental and technological applications of frequency comb-based technologies extended to the THz spectral range. Including the development of tunable ultra-low phase noise radio-frequency sources and measurement equipment like vector spectral analyzers for 6G.

Perspectives